The XC2028_I2C_FLUSH only needs to be implemented on a few
devices. Others can safely ignore it.
That prevents filling the dmesg with lots of messages like:
	dib0700: stk7700ph_xc3028_callback: unknown command 2, arg 0
Cc: stable@vger.kernel.org
Fixes: 4d37ece757a8 ("[media] tuner/xc2028: Add I2C flush callback")
Reported-by: Enrico Mioso <mrkiko.rs@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
        case XC2028_RESET_CLK:
                deb_info("%s: XC2028_RESET_CLK %d\n", __func__, arg);
                break;
+       case XC2028_I2C_FLUSH:
+               break;
        default:
                deb_info("%s: unknown command %d, arg %d\n", __func__,
                         command, arg);
 
                state->dib7000p_ops.set_gpio(adap->fe_adap[0].fe, 8, 0, 1);
                break;
        case XC2028_RESET_CLK:
+       case XC2028_I2C_FLUSH:
                break;
        default:
                err("%s: unknown command %d, arg %d\n", __func__,